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Growth Rates and Carbohydrate Fluxes within the Elongation Zone of Tall Fescue Leaf Blades

Growth Rates and Carbohydrate Fluxes within the Elongation Zone of Tall Fescue Leaf Blades Abstract Investigations were performed to better understand the carbon economy in the elongation zone of tall fescue leaf blades. Plants were grown at constant 21°C and continuous 300 micromoles per square meter per second photosynthetic photon flux density where leaf elongation was steady for several days. Elongation occurred in the basal 20 mm of the blade (0-20 millimeters above the ligule) and was maximum at 9 to 12 millimeters. Eight 3-millimeter long segments were sampled along the length of the elongation zone and analyzed for water-soluble carbohydrates. Sucrose concentration was high in the zone of cell division (0-6 millimeters) whereas monosaccharide concentration was high at and distal to the location where cell elongation terminated (20 millimeters). Fructan concentration increased in the basal part, then remained constant at about 85% of the total mass of water-soluble carbohydrates through the remainder of the elongation zone. Data on spatial distribution of growth velocities and substance contents (e.g. microgram fructan per millimeter leaf length) were used to calculate local net rates of substance deposition (i.e. excess rates of substance synthesis and/or import over substance degradation and/or export) and local rates of sucrose import. Rates of sucrose import and net deposition of fructan were positively associated with local elongation rate, whereas net rates of sucrose deposition were high in the zone of cell division and those of monosaccharide were high near the termination of elongation. At the location of most active elongation imported sucrose (29.5 milligrams per square decimeter per hour) was used largely for synthesis of structural components (52%) and fructan (41%). 2 Recipient of a scholarship from the Swiss National Science Foundation. Present address: Institut für Pflanzenbau, Universität Bonn, Katzenburgweg 5, D-5300 Bonn 1, Federal Republic of Germany. 1 Supported by United States Department of Agriculture CRGO and Missouri Agricultural Experiment Station, Journal Series No. 10286. This content is only available as a PDF. © 1987 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Physiology Oxford University Press

Growth Rates and Carbohydrate Fluxes within the Elongation Zone of Tall Fescue Leaf Blades

Schnyder, Hans; Nelson, Curtis J.
Plant Physiology , Volume 85 (2) – Oct 1, 1987
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References (10)

Publisher
Oxford University Press
Copyright
Copyright © 2021 American Society of Plant Biologists
ISSN
0032-0889
eISSN
1532-2548
DOI
10.1104/pp.85.2.548
Publisher site
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Abstract

Abstract Investigations were performed to better understand the carbon economy in the elongation zone of tall fescue leaf blades. Plants were grown at constant 21°C and continuous 300 micromoles per square meter per second photosynthetic photon flux density where leaf elongation was steady for several days. Elongation occurred in the basal 20 mm of the blade (0-20 millimeters above the ligule) and was maximum at 9 to 12 millimeters. Eight 3-millimeter long segments were sampled along the length of the elongation zone and analyzed for water-soluble carbohydrates. Sucrose concentration was high in the zone of cell division (0-6 millimeters) whereas monosaccharide concentration was high at and distal to the location where cell elongation terminated (20 millimeters). Fructan concentration increased in the basal part, then remained constant at about 85% of the total mass of water-soluble carbohydrates through the remainder of the elongation zone. Data on spatial distribution of growth velocities and substance contents (e.g. microgram fructan per millimeter leaf length) were used to calculate local net rates of substance deposition (i.e. excess rates of substance synthesis and/or import over substance degradation and/or export) and local rates of sucrose import. Rates of sucrose import and net deposition of fructan were positively associated with local elongation rate, whereas net rates of sucrose deposition were high in the zone of cell division and those of monosaccharide were high near the termination of elongation. At the location of most active elongation imported sucrose (29.5 milligrams per square decimeter per hour) was used largely for synthesis of structural components (52%) and fructan (41%). 2 Recipient of a scholarship from the Swiss National Science Foundation. Present address: Institut für Pflanzenbau, Universität Bonn, Katzenburgweg 5, D-5300 Bonn 1, Federal Republic of Germany. 1 Supported by United States Department of Agriculture CRGO and Missouri Agricultural Experiment Station, Journal Series No. 10286. This content is only available as a PDF. © 1987 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Journal

Plant Physiology – Oxford University Press

Published: Oct 1, 1987

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